Straight answers
Know what runs where.
The public product is a browser-based Stockfish practice board. Engine analysis and move feedback work on the site. Natural-language coaching is an optional local development feature, and the public site does not ask for an AI provider key.
- No account
- No subscription
- Browser-local engine
- Optional local AI development tools
What is Chess Coach?
Chess Coach is a browser game for practicing against Stockfish 18. Choose from six engine levels and an optional clock, then use the evaluation bar, move labels, best-move hint, undo, and board flip to review the game.
Does Stockfish run on my device?
Yes. Stockfish loads only after you select Start practice. It runs as WebAssembly in a browser Web Worker, so the chess position and engine analysis stay on your device.
How does move feedback work?
Stockfish compares your move with its preferred line and measures the evaluation change. Chess Coach turns that difference into a Best, Good, Inaccuracy, Mistake, or Blunder label.
Are natural-language AI explanations available on the public site?
No. They are an optional development feature that uses authenticated local Claude Code, Codex, or Gemini CLI tools through a local bridge. The public site does not accept provider API keys or send positions to a hosted AI proxy.
Is Chess Coach free?
Yes. The public game, evaluation, move labels, hints, and clocks are free. There is no account or subscription.
Can I pause a game and return later?
Yes. The current game, board orientation, difficulty, move history, clock setting, and remaining time are saved in your browser's localStorage.